The present invention relates to an apparatus for guiding an endless paper web and in particular to an apparatus for guiding an endless paper web without making use of perforated edges or transport pins to a subsequent paper processing means.
The present invention relates to an apparatus for guiding an endless paper web and in particular to an apparatus for guiding an endless paper web without making use of perforated edges or transport pins to a subsequent paper processing means.
In the prior art various apparatuses for guiding an endless paper web e.g. to a paper processing system are known. For achieving the straightest possible movement of the paper e.g. through a paper cutter or a printer, one method of implementing a paper guide means is the use of so-called traction means in the case of which transport holes punched into the paper web on both sides thereof are engaged by pins for transporting the paper.
One disadvantage of this paper guide means is to be seen in the fact that, for providing the perforated edges, the paper web must first be taken to a ready-to-use manufacturing apparatus by the producer before it can be supplied to the final consumer. In addition, the transport holes are frequently cut off from the lateral edges of the paper web for optical or other reasons in the means used for further processing, and this entails, in turn, an unnecessary consumption of paper and unnecessary waste paper and it necessitates an edge cutting means.
In the case of a further apparatus for guiding an endless paper web known on the prior art, the straight movement of the paper web is achieved by means of web-edge control making use of adjustable guide and transport rolls.
A paper guide means of this kind requires a very complicated technical design with adjustable guide and transport rolls; in addition, it is very complicated to carry out the adjustments for guiding a paper web of the respective type of paper.
In the prior art, an apparatus is additionally known in the case of which a paper guide means, which is described in detail in FIG. 6. Comprises a trough structure 100 with a concave or convex surface 102 and shoulders 104. The shoulders 104 are provided for engagement with opposed edges of a paper web 106. The direct distance 108 between the shoulders 104 on both sides of the trough structure 100 is smaller than a width 110 of the paper web 106 when flat. The trough structure 100 has the effect that the paper web 106 is deformed with regard to its width 110 so that the distance 108 between edges along the longitudinal sides of the paper web 106 in the trough structure 100 is smaller than the width 110 between the edges of the trough structure. When the apparatus is in use, the paper web 106 moves from an entrance end 112 to an exit end 114 through the trough structure 100. The shoulders 104 engage the paper edged so that the paper is help in the trough structure and guided along a straight line.
The paper web 106 moves through the trough structure 100 to a flat surface 116. This flat surface 116 extends from the concave surface 102 (support structure) of the exit end 114 of the trough structure 100 to the straightening plows 118. The flat surface 116 is additionally provided with a central opening 120. The opening 120 has arranged therein the driving roll 122. The driving roll 122 is arranged in the opening 120 in a vertical plane in such a way that an outer rubber surface 124 of the driving roll 122 is located slightly above the flat surface 116. The outer layer 124 of the driving roll 122 engages the lower surface of the paper web 106 as soon as this paper web 106 moves over the flat surface 116 and conveys the paper web 106 by means of the rotation of the driving roll 122.
The straightening plows 118 are provided at the end of the flat surface 116 opposite the trough structure 100, as can be seen in FIG. 6. The straightening plows 118 comprise an upper lip 124 and a lower lip 126. In this arrangement, a pressure roll 128 is used for applying a pressure on a paper web passing between the pressure roll 106 will be maintained in contact with the driving roll 122.
The direction of movement of the paper web 106 through the trough structure 100 is indicated by the arrow 130 in FIG. 6.
Due to the fact that the driving roll 122 is arranged such that it projects through the opening 120 above the flat surface 116, an axial displaceability of the driving roll 122 is not possible.
An apparatus of this type is known e.g. from U.S. Pat. No. 5,213,246, which achieves paper guidance by means of a trough structure in which the paper web flows, the trough structure being formed in one piece. Due to the structural design of this trough structure, a separate trough structure is required for each paper web width. In addition, when the paper web running through the trough structure is very broad and thin, only a very slight increase in the stiffness of the paper web can be reckoned with.
In view of the above-mentioned facts, known paper transport means are only capable of guiding paper webs having a specific width and paper thickness or it is necessary to use either so-called traction means or a complicated web-edge control for guaranteeing that the paper web moves along a straight path e.g. to a paper processing system.
It is the object of the present invention to provide an apparatus for guiding an endless paper web which is capable of handling the paper web independently of its width and thickness without using any traction means or web-edge control.
The present invention is an apparatus for guiding an endless paper web having:
two lateral guide devices guiding the paper web at the longitudinal edges thereof;
a deflector with the aid of which the paper web is deflected at least once from its direction of movement while it is moving between the lateral guide devices; and
a first transport roll on a drivable shaft and a second transport roll for applying a feed force to the paper web passing between the first and the second transport roll.
The present invention is based on the finding that an increase in the stiffness of the paper web is achieved by vertically deflecting the paper web from the direction of movement, whereby the paper web will be prevented from ascending the lateral guide means and whereby damage to the paper web will be avoided when the paper web comes into lateral contact with the lateral guide means.
An advantage of the present invention is to be seen in the fact that paper costs can be reduced essentially, since the paper webs can be used with an unperforated edge thus avoiding the necessity of laterally cutting off the transport holes for optical or other reasons in the means used for further processing; this avoids an unnecessary consumption of paper and unnecessary waste paper, and additional edge cutting means can be dispensed with.
According to a preferred embodiment of the present invention, a wave-shaped path of movement or rather a wave-shaped deflection of the paper web from its direction of movement is achieved by means of a plurality of round bars between which the paper web passes. Since the deflection of the paper web can be adjusted to different paper web widths, paper thicknesses and strengths by adjusting one of the round bars and the distance of the lateral guide means, the apparatus for guiding an endless paper web is capable of handling paper webs with arbitrary paper web widths, paper thicknesses and strengths, respectively.